cn.hutool.core.map

Class SafeConcurrentHashMap<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

java.util.concurrent.ConcurrentHashMap<K,V>

cn.hutool.core.map.SafeConcurrentHashMap<K,V>

Type Parameters:

K - 键类型

V - 值类型

All Implemented Interfaces:

Serializable, ConcurrentMap<K,V>, Map<K,V>

public class SafeConcurrentHashMap<K,V>
extends ConcurrentHashMap<K,V>

安全的ConcurrentHashMap实现
此类用于解决在JDK8中调用ConcurrentHashMap.computeIfAbsent(Object, Function)可能造成的死循环问题。
方法来自Dubbo，见：issues#2349

相关bug见：@see https://bugs.openjdk.java.net/browse/JDK-8161372

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.concurrent.ConcurrentHashMap

ConcurrentHashMap.KeySetView<K,V>

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
SafeConcurrentHashMap() 构造，默认初始大小（16）
SafeConcurrentHashMap(int initialCapacity) 构造
SafeConcurrentHashMap(int initialCapacity, float loadFactor) 构造
SafeConcurrentHashMap(int initialCapacity, float loadFactor, int concurrencyLevel) 构造
SafeConcurrentHashMap(Map<? extends K,? extends V> m) 构造

Method Summary

Modifier and Type	Method and Description
V	computeIfAbsent(K key, Function<? super K,? extends V> mappingFunction)

Methods inherited from class java.util.concurrent.ConcurrentHashMap

clear, compute, computeIfPresent, contains, containsKey, containsValue, elements, entrySet, equals, forEach, forEach, forEach, forEachEntry, forEachEntry, forEachKey, forEachKey, forEachValue, forEachValue, get, getOrDefault, hashCode, isEmpty, keys, keySet, keySet, mappingCount, merge, newKeySet, newKeySet, put, putAll, putIfAbsent, reduce, reduceEntries, reduceEntries, reduceEntriesToDouble, reduceEntriesToInt, reduceEntriesToLong, reduceKeys, reduceKeys, reduceKeysToDouble, reduceKeysToInt, reduceKeysToLong, reduceToDouble, reduceToInt, reduceToLong, reduceValues, reduceValues, reduceValuesToDouble, reduceValuesToInt, reduceValuesToLong, remove, remove, replace, replace, replaceAll, search, searchEntries, searchKeys, searchValues, size, toString, values

Methods inherited from class java.util.AbstractMap

clone

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

SafeConcurrentHashMap

public SafeConcurrentHashMap()

构造，默认初始大小（16）

SafeConcurrentHashMap

public SafeConcurrentHashMap(int initialCapacity)

构造

Parameters:

initialCapacity - 预估初始大小

SafeConcurrentHashMap

public SafeConcurrentHashMap(Map<? extends K,? extends V> m)

构造

Parameters:

m - 初始键值对

SafeConcurrentHashMap

public SafeConcurrentHashMap(int initialCapacity,
                             float loadFactor)

构造

Parameters:

initialCapacity - 初始容量

loadFactor - 增长系数

SafeConcurrentHashMap

public SafeConcurrentHashMap(int initialCapacity,
                             float loadFactor,
                             int concurrencyLevel)

构造

Parameters:

initialCapacity - 初始容量

loadFactor - 增长系数

concurrencyLevel - 并发级别，即Segment的个数

Method Detail

computeIfAbsent

public V computeIfAbsent(K key,
                         Function<? super K,? extends V> mappingFunction)

Specified by:

computeIfAbsent in interface ConcurrentMap<K,V>

Specified by:

computeIfAbsent in interface Map<K,V>

Overrides:

computeIfAbsent in class ConcurrentHashMap<K,V>